One problem related to timing tensioner has been reported for the 2006 Mini Cooper S. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2006 Mini Cooper S based on all problems reported for the 2006 Cooper S.
Loud noise/rattle at idle. Loose camshaft timing chain due to tensioner failure. It would appear from several forums that this is fairly common problem that dealers are refusing to fix since warranty is expired.